Let’s call the goal you’re trying to reach “Point G”.
And let’s call the best place the data can lead you to “Point D”.
Note that Point D is near Point G, but it’s not exactly the same point.
The problem is this: the thing your data is measuring is not *exactly* the thing you’re trying to accomplish.
The real world isn’t two-dimensional, and the data doesn’t lead you in a straight line. But the phenomenon does, I believe, exist in the wild. And it’s becoming more and more common as computers make data-driven processes easy for organizations and industries to implement and follow.